GENDA is a Fortran77 sofware package for the numerical solution of nonlinear
differential-algebraic equations (DAEs) of arbitrary index

0=F(x,x',t)

(1)

on the domain [t0,tf] together with an initial condition

x(t0)=x0

An important invariant in the analysis of DAEs is the so called
strangeness index, which generalizes the differentiation index
[2], [3], [5] for systems
with undetermined components [B]. It is known that many of the
standard integration methods for general DAEs require the system to have
differentiation index not higher than one. If this condition is not valid or
if the DAE has undetermined components, then the standard methods as implemented in
codes like DASSL of Petzold [8] or LIMEX of
Deuflhard/Hairer/Zugck [4] may fail.
The implementation of GENDA is based on the construction of the discretization
scheme introduced in [A], which transforms the system into a
strangeness-free DAE with the same local solution set. The resulting
strangeness-free system is allowed to
have nonuniqueness in the solution set or inconsistency in the initial values or
inhomogeneities. But this information is now available to the user and systems
with such properties can be treated in a least squares sense.
In the case that the DAE is found to be uniquely solvable, GENDA is able to
compute a
consistent initial value and apply an integration scheme for
DAEs. In GENDA Runge-Kutta scheme of type RADAU IIa of order 5
[6], [7] is implemented.

Technical questions about the proper use of a software package should be directed to the authors of that package.

Disclaimer:

Warranty disclaimer: The software is supplied "as is"
without warranty of any kind.
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do not warrant that the software will function
uninterrupted, that it is error-free or that any errors will
be corrected.

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